A fan start-stop method and system

Abstract

The application relates to the technical field of wind power generation, and particularly discloses a wind turbine starting and stopping method and system, which comprises the following steps: after receiving a starting signal, the current wind speed is acquired, and the wind wheel starting rotating speed is estimated according to the current wind speed; based on the wind wheel starting rotating speed, the pitch angle is adjusted, and the wind wheel rotating speed is waited to reach a preset grid-connected rotating speed; after entering the grid-connected state, the running state of the wind turbine is switched through preset interval division; after receiving a shutdown signal, the current wind speed is acquired, and the running state interval of the current wind turbine is confirmed, the wind wheel braking rotating speed is calculated according to the current wind turbine running state interval; and based on the wind wheel braking rotating speed, shutdown control is performed. According to the application, the corresponding wind wheel starting rotating speed and wind wheel braking rotating speed are set according to the current wind speed and the current working state of the wind turbine, so that the starting and shutdown of the wind turbine are dynamically regulated and controlled, which can help reduce the load of the wind turbine and improve the power generation efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of wind power generation technology, in particular to a wind turbine start-stop method and system. BACKGROUND

[0002] The wind turbine, i.e. the wind turbine generator, is a device for converting wind energy into electric energy. The state parameters of the wind turbine generator, such as wind speed, wind wheel speed, generator power, etc., can be obtained through the subsystems and sensors of the wind turbine generator, and the operation of the wind turbine generator can be realized through the analysis and processing of the control algorithm combined with external control requirements.

[0003] Since the wind turbine generator can only output electric energy to the power grid when the wind speed is greater than the wind speed threshold, at this time, the wind turbine generator should be started as soon as possible to avoid loss of power generation. Correspondingly, during the grid-connected power generation stage, if the wind speed continues to decrease and cannot output electric energy to the power grid, the wind turbine generator may consume a certain amount of electric energy from the power grid to maintain its working state, at this time, the wind turbine generator should be stopped as soon as possible to reduce the power consumption.

[0004] In the prior art, the start and stop control of the wind turbine generator is generally based on wind speed and generator speed, but in actual wind turbine start-stop control, there is usually a lack of comprehensive consideration of the current wind speed and the current working state of the wind turbine, resulting in additional power loss during wind turbine start-stop. SUMMARY

[0005] The purpose of the present application is to provide a wind turbine start-stop method and system, which combines the current wind speed to control the start rhythm when the wind turbine is started, and generates a corresponding start-stop strategy according to the current working state when it is stopped, thereby reducing the additional loss of electric power.

[0006] In the first aspect, the present application provides a wind turbine start-stop method, which adopts the following technical solution:

[0007] After receiving the start signal, the current wind speed is obtained, and the wind wheel start speed is estimated according to the current wind speed;

[0008] Based on the wind wheel start speed, the pitch angle is adjusted, and after the wind wheel speed reaches the preset grid-connected speed, the wind turbine enters the grid-connected state;

[0009] After entering the grid-connected state, the running state of the wind turbine is switched through the preset interval division;

[0010] After receiving the stop signal, the current wind speed is obtained and the current wind turbine running state interval is confirmed, and the wind wheel braking speed is calculated according to the current wind turbine running state interval;

[0011] Based on the wind wheel braking speed, the stop control is performed.

[0012] By the technical scheme, in the process of starting the fan, the rotor starting rotating speed is taken as the parameter of the pitch angle adjustment, so as to avoid the pitch angle from not reaching the optimal pitch angle state after entering the grid-connected state, thereby causing the loss of power generation; in the process of stopping the fan, the rotor is dynamically braked and controlled through the rotor braking rotating speed, so as to avoid the imbalance of the rotor rotating speed, thereby avoiding the additional load and the loss of power caused to the fan.

[0013] Optionally, the rotor starting rotating speed is estimated according to the current wind speed, and the method comprises the following steps.

[0014] The rotor starting rotating speed is set as a variable parameter.

[0015] The time from the rotor starting rotating speed to the preset grid-connected rotating speed under the current wind speed is estimated through the preset initial pitch angle, and the time is recorded as a first time.

[0016] The time from the rotor starting rotating speed to the preset grid-connected rotating speed under the current wind speed is estimated through the preset grid-connected pitch angle, and the time is recorded as a second time.

[0017] Based on the first time and the second time, a time difference value is obtained, and the time difference value is recorded as a rotating speed deviation time.

[0018] According to the rotating speed deviation time, a target function is constructed by taking the time difference value between the preset pitch adjustment time and the rotating speed deviation time as minimum, and the rotor starting rotating speed is calculated through a preset method.

[0019] Optionally, the pitch angle is adjusted based on the rotor starting rotating speed, and the fan enters the grid-connected state after the rotor rotating speed reaches the preset grid-connected rotating speed, and the method comprises the following steps.

[0020] After the fan starts, the pitch angle is adjusted to the preset initial pitch angle.

[0021] When the rotor rotating speed reaches the rotor starting rotating speed, the pitch angle is adjusted to the preset grid-connected pitch angle, and then the rotor rotating speed is waited to rise; when the rotor rotating speed reaches the preset grid-connected rotating speed, the fan enters the grid-connected state.

[0022] Optionally, the operation range of the fan comprises a first interval, a second interval, a third interval and a fourth interval, which are respectively referred to as a first interval, a second interval, a third interval and a fourth interval.

[0023] Optionally, the operation state of the fan is switched through preset interval division, and the method comprises the following steps.

[0024] When the generator power reaches the minimum power corresponding to the optimal tip speed ratio in the first interval, the second interval is switched in.

[0025] When the generator power is lower than the minimum power corresponding to the optimal tip speed ratio in the second interval, the first interval is returned to, and when the wind turbine speed reaches the preset rated speed and the generator power continues to rise, the third interval is entered;

[0026] When the wind turbine speed drops below the preset rated speed in the third interval, the second interval is returned to, and when the generator power reaches the rated power and the wind speed continues to rise, the fourth interval is entered;

[0027] When the generator power drops below the preset rated power in the fourth interval, the third interval is returned to.

[0028] Optionally, the shutdown signal is divided into a normal shutdown signal and an abnormal shutdown signal, and after receiving the shutdown signal, the current wind speed is acquired and the running state interval of the current wind turbine is confirmed, the wind turbine braking speed is calculated and acquired according to the running state interval of the current wind turbine, including:

[0029] If the current shutdown signal is an abnormal shutdown signal, the source of the current abnormal shutdown signal is acquired, and the abnormal risk level is evaluated according to the current wind speed and the running state interval of the wind turbine;

[0030] If the abnormal risk level reaches a preset risk level, a first prompt information is output, and the first prompt information indicates that the risk level is too high and rapid shutdown or emergency shutdown needs to be performed;

[0031] If the current shutdown signal is a normal shutdown signal, the current wind speed is acquired and the running state interval of the current wind turbine is confirmed, and the wind turbine braking speed is calculated and acquired according to the running state interval of the current wind turbine.

[0032] Optionally, the wind turbine braking speed is calculated and acquired according to the running state interval of the current wind turbine, including:

[0033] According to the running state interval of the current wind turbine, the current wind turbine speed and the pitch angle size are confirmed;

[0034] According to a preset pitch speed, the time required for adjusting the pitch angle from the current pitch angle to the fully feathered state is calculated and recorded as a feathering time, and the gradient of the nonlinear relationship between the wind turbine speed and the pitch angle at the current wind speed is derived, and the maximum gradient descent direction is selected to calculate a speed increment coefficient;

[0035] According to the speed increment coefficient and the feathering time, the wind turbine braking speed is calculated and acquired.

[0036] Optionally, the shutdown control is performed based on the wind turbine braking speed, including:

[0037] After receiving the wind turbine shutdown signal, the pitch angle is adjusted to make the blade feathered, and when the wind turbine speed decreases to the wind turbine braking speed, the wind turbine braking is started;

[0038] When the wind wheel rotation speed drops to the preset safety rotation speed after the wind wheel brake is turned on, a second prompt information is output, and the second prompt information indicates that the fan has completed the shutdown operation.

[0039] In a second aspect, the application provides a fan start-stop system, comprising:

[0040] The wind wheel start rotation speed acquisition module 101 is configured to acquire the current wind speed after receiving the start signal, and estimate the wind wheel start rotation speed according to the current wind speed.

[0041] The fan start module 102 is configured to adjust the pitch angle based on the wind wheel start rotation speed, and enter the grid-connected state after the wind wheel rotation speed reaches the preset grid-connected rotation speed.

[0042] The working state switching module 103 is configured to switch the running state of the fan through preset interval division after entering the grid-connected state.

[0043] The wind wheel brake rotation speed acquisition module 104 is configured to acquire the current wind speed and confirm the running state interval of the current fan after receiving the shutdown signal, and calculate the wind wheel brake rotation speed according to the running state interval of the current fan.

[0044] The fan shutdown module 105 is configured to perform shutdown control based on the wind wheel brake rotation speed.

[0045] In a third aspect, the application provides a computer readable storage medium storing a computer program capable of being loaded and executed by a processor to perform the above-mentioned fan start-stop method.

[0046] To sum up, first, the corresponding wind wheel start rotation speed and wind wheel brake rotation speed are set according to the current wind speed and the current working state of the fan, so as to dynamically control the start and shutdown of the fan, which can help improve the capture of wind energy and reduce the additional load on the fan. In addition, the working state switching of the fan in the grid-connected stage not only maximizes the wind energy utilization efficiency, but also provides a basis for dynamic control during shutdown. Furthermore, by subdividing the shutdown signal, the shutdown control strategy can also be adjusted to reduce the additional load on the wind wheel during shutdown. BRIEF DESCRIPTION OF DRAWINGS

[0047] Figure 1 is a flowchart of a fan start-stop method provided by an embodiment of the application;

[0048] Figure 2 is a flowchart of the current wind speed estimation and acquisition of the wind wheel start rotation speed provided by an embodiment of the application;

[0049] Figure 3is a flowchart of adjusting a shutdown scheme according to a type of shutdown signal provided by an embodiment of the present application;

[0050] Figure 4 is a flowchart of calculating a wind wheel braking speed according to a current wind turbine operating state interval provided by an embodiment of the present application;

[0051] Figure 5 is a schematic diagram of a wind turbine start-stop system provided by an embodiment of the present application. DETAILED DESCRIPTION

[0052] The following will be described in detail below with reference to the accompanying Figure 1 - the accompanying Figure 5 The present application will be further described in detail.

[0053] The present application provides a wind turbine start-stop method, referring to Figure 1 , comprising the following steps:

[0054] S100, after receiving a start signal, obtaining a current wind speed, and estimating a wind wheel start speed according to the current wind speed.

[0055] The wind wheel start speed indicates that when the wind turbine starts, the blade pitch angle is adjusted when the wind wheel speed reaches a certain value, so that the wind turbine can quickly enter a grid-connected state in the form of the optimal pitch angle at the current wind speed. The so-called optimal pitch angle is generally 0 degrees, also known as the minimum pitch angle, because the wind energy utilization coefficient is maximum when the pitch angle is 0 degrees, that is, the power generation efficiency is highest. The so-called grid-connected state means physical connection with the power grid.

[0056] In the wind turbine start phase, when the average wind speed in a certain time is detected to reach the power generation requirement, a start signal is sent to the wind turbine in standby state, and then the wind turbine starts. In general, after the wind turbine starts, the pitch angle is adjusted, that is, the pitch is opened, the wind wheel speed is increased by changing the impact angle of the airflow on the wind wheel blades, and after the pitch angle is 0 degrees, the wind wheel speed reaches the set grid-connected speed, and then enters the grid-connected state.

[0057] Because it is considered that when the unit is in standby state, the wind wheel blades are in fully closed state, that is, the pitch angle is about 90 degrees, even after receiving the start signal, the pitch angle is first adjusted to a certain angle, for example, about 50 degrees, however, when the wind speed is too fast, the speed of the wind wheel will also increase accordingly, so it is still possible that when the wind wheel speed reaches the set grid-connected speed, the pitch angle has not been adjusted to the optimal pitch angle state, which means that after entering the grid-connected state, there is a period of time when the maximum wind energy cannot be captured.

[0058] Therefore, the pitch angle should be adjusted as much as possible before grid connection, rather than after grid connection, so as to maximize the wind energy capture benefit. Therefore, after receiving the start signal, in addition to adjusting the pitch angle in advance, the speed of the wind turbine under different pitch angles at the current wind speed should also be considered, so that the pitch angle can be adjusted to the grid-connected state in the first time without affecting the normal start of the unit.

[0059] Therefore, in the embodiments of the present application, the concept of wind turbine start speed is proposed, that is, after receiving the start signal, the pitch angle is first adjusted to a certain angle, for example, 50 degrees in the above, and then the pitch angle is adjusted to 0 degrees after the wind turbine speed reaches the wind turbine start speed, while the wind turbine speed is in a continuous rising state. When the pitch angle is adjusted to 0 degrees, the wind turbine speed is close to the set grid-connected speed, so that the maximum wind energy capture can be realized under normal pitch angle adjustment.

[0060] The acquisition of the wind turbine start speed mainly depends on the current wind speed and the change of the wind turbine speed corresponding to different pitch angles under the current wind speed.

[0061] Specifically, referring to Figure 2 , the wind turbine start speed is estimated and acquired according to the current wind speed, including the following steps:

[0062] S110, setting the wind turbine start speed as a variable parameter.

[0063] S120, estimating the time from the wind turbine start speed to the preset grid-connected speed under the current wind speed through the preset initial pitch angle, and recording the time as the first time.

[0064] S130, estimating the time from the wind turbine start speed to the preset grid-connected speed under the current wind speed through the preset grid-connected pitch angle, and recording the time as the second time.

[0065] S140, acquiring the time difference value based on the first time and the second time, and recording the time difference value as the speed deviation time.

[0066] S150, according to the speed deviation time, constructing a target function by minimizing the time difference value through the preset pitch angle adjustment time, and calculating the wind turbine start speed through the preset method.

[0067] The initial pitch angle is the pitch angle adjusted to a certain angle, for example, 50 degrees or so, after receiving the start signal, which is recorded as β1 in the above. The grid-connected pitch angle is the optimal pitch angle when entering the grid-connected state, for example, 0 degrees or so, which is recorded as β2 in the above. The preset grid-connected speed represents the minimum wind turbine speed allowed to enter the grid-connected state, which is recorded as ωg in the above.

[0068] First, let the wind turbine startup speed be considered as a variable parameter, denoted as α. Based on the fact that different propeller angles at the same wind speed will produce different torque-speed curves, the increase in wind turbine speed at the current wind speed with a propeller angle of β1 can be expressed as: From the wind turbine starting speed α to the preset grid-connected speed The time, denoted as the first time, is represented by t1. Based on the relationship between the increase in wind turbine speed and the blade pitch angle, t1 can be expressed as:

[0069]

[0070] Similarly, when the pitch angle is β2, the increase in wind turbine speed can be expressed as: From the wind turbine starting speed α to the preset grid-connected speed The time interval is denoted as the second time interval, and represented by t2. Based on the relationship between the increase in wind turbine speed and the blade pitch angle, t2 can be expressed as:

[0071]

[0072] t1 and t2 represent two extreme cases, where the pitch angles are fixed at β1 and β2, respectively. However, in reality, the pitch angle is in the process of adjusting from β1 to β2, and the turbine speed increase is continuously increasing during this adjustment process. Therefore, the time difference between t1 and t2 is an idealized maximum usable time, denoted here as the speed deviation time, i.e., (t2-t1). The actual time difference is smaller. Our goal is to adjust the initial pitch angle to a grid-connected pitch angle within this time difference, while simultaneously ensuring the turbine speed reaches the grid-connected speed. Only under these conditions can the wind energy capture benefit be maximized.

[0073] Furthermore, since adjusting the pitch angle also requires a certain amount of time, the blades typically adjust the pitch at a rate not exceeding 10 degrees per second. This is because excessively fast blade pitch adjustments would overload the pitch system and potentially damage its internal components. Therefore, based on the current unit's pitch speed setting, the time required for the pitch angle to adjust from the initial pitch angle β1 to the grid-connectable pitch angle β2 can be obtained; this is the preset pitch adjustment time, denoted here as...

[0074] Given the requirement to adjust the pitch angle from the initial pitch angle β1 to the grid-connectable pitch angle β2, it is desirable to minimize the speed deviation time. This allows for faster grid connection and maximizes wind energy capture benefits. This speed deviation time is determined by the turbine startup speed, i.e., the variable parameter α. Therefore, the objective function can be constructed by minimizing the difference between the speed deviation time and the pitch adjustment time, i.e.:

[0075]

[0076] Substitute t1 and t2, and the value of a can be solved, that is, the starting speed of the wind wheel.

[0077] S200, based on the starting speed of the wind wheel, adjust the pitch angle, and wait for the wind wheel speed to reach the preset grid-connected speed to enter the grid-connected state.

[0078] In the embodiment of the application, after obtaining the starting speed of the wind wheel according to the current wind speed, the starting control of the wind turbine can be performed according to the starting speed of the wind wheel.

[0079] Specifically, based on the starting speed of the wind wheel, adjust the pitch angle, and wait for the wind wheel speed to reach the preset grid-connected speed to enter the grid-connected state, including the following steps:

[0080] S210, after the wind turbine starting state, adjust the pitch angle to the preset initial pitch angle.

[0081] S220, when the wind wheel speed reaches the starting speed of the wind wheel, adjust the pitch angle to the preset grid-connected pitch angle, and then wait for the wind wheel speed to rise.

[0082] S230, when the wind wheel speed reaches the preset grid-connected speed, enter the grid-connected state.

[0083] In the embodiment of the application, when the wind turbine starting signal is received, the wind turbine enters the starting state, first adjusts the pitch angle to the preset initial pitch angle, that is, the 50 degrees mentioned above. The reason for adjusting to this angle is that the speed change speed is not too inclined at this angle, and the swing space is large, which is convenient for adjustment at any time. Of course, it can also be around 45 degrees. The setting of the initial pitch angle is not limited in the application.

[0084] After adjusting to the initial pitch angle, wait for the wind wheel speed to reach the starting speed of the wind wheel. When the wind wheel speed reaches the starting speed of the wind wheel, start adjusting the pitch angle to the preset grid-connected pitch angle, and at the same time, wait for the wind wheel speed to rise. When the wind wheel speed reaches the preset grid-connected speed, enter the grid-connected state, that is, enter the power generation stage.

[0085] S300, after entering the grid-connected state, switch the running state of the wind turbine through the preset interval division.

[0086] Since in the grid-connected stage, that is, in the power generation process, as a variable speed constant frequency wind turbine, in order to realize the maximum wind energy capture benefit, the wind speed change is tracked at low wind speed, the best tip speed ratio is maintained during operation to obtain the maximum wind energy, and the blade pitch angle is adjusted by the change of the wind wheel speed at high wind speed, so that the output power is more stable while ensuring the safe and stable operation of the wind turbine.

[0087] Therefore, after entering the grid-connected stage, the wind wheel speed value is in a state of change, and the working state of the wind turbine is adjusted from time to time during the entire power generation stage, so that the power generation efficiency is higher.

[0088] In the embodiment of the application, in order to better track the working state of the wind turbine in the power generation stage, the working state of the wind turbine in the power generation stage is divided into intervals, so that the shutdown strategy can be adjusted according to the current working state of the wind turbine when the wind turbine is shut down.

[0089] Specifically, the preset interval division includes an initial grid-connected transition interval, an optimal tip speed ratio interval, a rated speed interval, and a rated power continuous control interval, which are respectively referred to as a first interval, a second interval, a third interval, and a fourth interval.

[0090] In the grid-connected stage, the wind turbine switches the intervals according to the current wind speed and generator power, and in combination with the maximization of the wind energy utilization coefficient.

[0091] Specifically, the running state of the wind turbine is switched through the preset interval division, including the following steps:

[0092] S310, when the generator power reaches the minimum power corresponding to the optimal tip speed ratio, the second interval is switched in when the wind wheel speed is in the first interval.

[0093] S320, when the generator power is lower than the minimum power corresponding to the optimal tip speed ratio, the first interval is switched back to when the wind wheel speed reaches the preset rated speed and the generator power continues to rise, and the third interval is switched in.

[0094] S330, when the wind wheel speed drops below the preset rated speed, the second interval is switched back to when the generator power reaches the preset rated power and the wind speed continues to rise, and the fourth interval is switched in.

[0095] S340, when the generator power drops below the preset rated power, the third interval is switched back to.

[0096] The preset rated speed refers to the maximum wind wheel speed under the rated power condition, and the preset rated power refers to the limit of the unit power.

[0097] The initial grid-connected transition interval is the working state just after entering the grid-connected stage. The main work in this interval is to prepare for the optimal tip speed ratio. The tip speed ratio represents the ratio of the blade tip line speed to the wind speed, which is an important parameter representing the performance of the wind turbine, or simply, it represents a state of a wind wheel under different wind speeds. When the state is the optimal tip speed ratio, the wind energy utilization coefficient is the highest.

[0098] In the initial grid-connection transition interval, the torque increases while the generator speed remains unchanged, but the generator power also increases due to the increase in torque, so when the generator power reaches the minimum power corresponding to the optimal tip speed ratio, the optimal tip speed ratio interval is entered.

[0099] The optimal tip speed ratio interval indicates that as the wind speed changes, the optimal tip speed ratio is maintained by adjusting the rotor speed, so that the utilization coefficient of wind energy is maximized. The rotor speed is related to the generator speed, and of course, it is also related to the pitch angle, but the current pitch angle in this interval has the highest wind energy capture benefit, so the pitch angle will not be adjusted temporarily. Therefore, in the optimal tip speed ratio interval, the rotor speed will change with the wind speed by controlling the generator speed to maintain a constant tip speed ratio to seek maximum wind energy capture.

[0100] In the optimal tip speed ratio interval, the points corresponding to the optimal tip speed ratio at different wind speeds can form an optimal wind energy utilization curve, also known as the best power curve. Therefore, when the wind speed increases, the generator speed can be controlled to increase the rotor speed according to the nonlinear relationship between the torque and the generator speed. When the rotor speed reaches the preset rated speed, the rotor speed needs to remain unchanged due to the limitation of the mechanical strength of the rotating parts of the unit, so the rated speed interval is entered.

[0101] Correspondingly, when the wind speed decreases, the generator speed is controlled to reduce the rotor speed, and at the same time, the generator power decreases. When the generator power is lower than the minimum power corresponding to the optimal tip speed ratio, the minimum power corresponding to the optimal tip speed ratio is the minimum value presented in the best power curve mentioned above. When the generator power is lower than this value, it is no longer possible to capture wind energy at the optimal tip speed ratio, so the initial grid-connection transition interval is returned.

[0102] In the rated speed interval, the tip speed ratio decreases with the increase of the wind speed because the rotor speed remains unchanged, but the generator power still increases with the increase of the wind speed. When the generator power reaches the rated power, which is the limit of the generator power, the rated power continuous control interval is entered. Correspondingly, when the wind speed decreases, the tip speed ratio increases, and when the tip speed ratio returns to the optimal tip speed ratio, the rotor speed is adjusted again. When the rotor speed decreases below the rated speed, the optimal tip speed ratio interval is returned.

[0103] In the rated power duration control interval, the unit is equivalent to enter the power constant area, with the increase of wind speed, because the generator power is constant, so it is impossible to adjust the wind wheel speed by mechanical means, so at this time the pitch will start to adjust, by changing the pitch angle, to change the angle of attack of the airflow to the blade, so as to change the wind wheel speed, so as to maintain the rated power constant operation under the condition of continuous increase of wind speed, but in the case of increasing wind speed, the tip speed ratio decreases faster than in the rated speed interval, which is equivalent to the unit operating with smaller wind energy utilization coefficient to maintain constant power.

[0104] Correspondingly, when the wind speed decreases, in order to maintain constant power, the pitch angle will rotate to the minimum pitch angle to increase the wind wheel speed, when the pitch angle reaches the minimum pitch angle, at this time it is impossible to adjust, that is, the constant power cannot be maintained, so the rated power will decrease, that is, it will cut back to the rated speed interval.

[0105] S400, after receiving the shutdown signal, acquiring the current wind speed and confirming the current wind turbine operating state interval, calculating the wind wheel braking speed according to the current wind turbine operating state interval.

[0106] Among them, the shutdown signal is divided into normal shutdown signal and abnormal shutdown signal, so-called normal shutdown is easy to understand, it may be that there is no need to generate electricity, let the wind turbine stop working and enter standby state, at this time it will generally be stopped by manual operation, and the corresponding wind turbine system will receive the normal shutdown signal.

[0107] And abnormal shutdown is abnormal forced shutdown, which is divided into two cases, one is that the unit appears fault, such as fault of power generation equipment, speed regulating device, etc., which is forced to stop for safety to troubleshoot and repair; The other is external environmental anomaly, the most typical one is that the wind speed is too high, when the wind speed reaches the cut-out wind speed, that is, the maximum wind speed of the unit connected to the grid, in order to avoid damage to the wind turbine in strong wind, the wind turbine will be stopped, because whether it is equipment failure or wind speed, the unit can get feedback through corresponding data monitoring, when the abnormality occurs, the corresponding shutdown signal, that is, the abnormal shutdown signal, will be sent.

[0108] Because no matter what reason for shutdown, the way of shutdown will not have too much difference, but considering the need to stop when the current wind turbine working state, it is still necessary to make corresponding adjustment, just like driving a car, when you need to stop, you will control the brake according to the current speed, and the wind turbine shutdown control principle is also comparable, so it is still necessary to highlight the dynamic adjustment of the shutdown process according to the current state of the wind turbine and the wind speed, in order to minimize the additional load on the wind turbine.

[0109] Specifically, seeFigure 3 After receiving the shutdown signal, the current wind speed is acquired and the current wind turbine operating state interval is confirmed, and the wind wheel braking speed is calculated according to the current wind turbine operating state interval, including the following steps:

[0110] S410, if the current shutdown signal is an abnormal shutdown signal, the current abnormal shutdown signal source is acquired, and the abnormal risk level is evaluated according to the current wind speed and the operating state interval of the wind turbine.

[0111] S420, if the abnormal risk level reaches the preset risk level, the first prompt information is output.

[0112] S430, if the current shutdown signal is a normal shutdown signal, the current wind speed is acquired and the current wind turbine operating state interval is confirmed, and the wind wheel braking speed is calculated according to the current wind turbine operating state interval.

[0113] First, it is still judged whether the current shutdown signal is a normal shutdown signal or an abnormal shutdown signal. If it is an abnormal shutdown signal, since it is considered that the fault may be related to the shutdown braking system of the wind turbine, or the fault is more serious and urgent, in addition to knowing the fault reason, the risk level also needs to be evaluated according to the current wind speed and the operating state interval of the wind turbine, so as to take countermeasures. Still taking driving a car as an example, when the car needs to stop during driving, a brake failure fault occurs. At this time, if the speed is very fast, the risk level will be high, and if the speed is very slow, the risk level will be relatively low. This is just a simple example and does not consider too complex a situation. The main purpose is still to illustrate that when the wind turbine needs to stop due to an abnormal signal, the current working state of the wind turbine also needs to be considered for more reasonable control and response.

[0114] According to the current abnormal shutdown signal source, the current wind speed and the operating state interval of the wind turbine, the abnormal risk level can be evaluated. If the abnormal risk level reaches the preset risk level, the first prompt information is output. Here, the preset risk level can be simply divided into three levels: high, medium and low. The so-called first prompt information indicates that the risk level is too high and needs to be stopped quickly or stopped urgently.

[0115] When the abnormal risk level is high, emergency shutdown is needed. Emergency shutdown is equivalent to triggering safety chain shutdown, which can be specifically divided into two cases: one is a variable pitch system failure, which will automatically disconnect the safety chain and execute feathering at the expected speed; the other is that the safety chain of other systems of the wind turbine is disconnected, resulting in the disconnection of the variable pitch safety chain and the execution of feathering.

[0116] When the abnormal risk level is medium, the fan master control instruction is accepted to complete the feathering, but the feathering speed is faster to achieve fast shutdown. When the abnormal risk level is primary, it is considered to be processed according to the normal shutdown signal. Therefore, the above-mentioned abnormal risk level reaching the preset risk level means that if the abnormal risk level reaches the medium or high level, the corresponding prompt information is output to take corresponding shutdown response measures.

[0117] If the current shutdown signal is a normal shutdown signal, the current wind speed is also obtained and the current fan operating state interval is confirmed, and then the current fan operating state interval is used to take targeted shutdown response. Considering that the speed of the wind wheel will be adjusted according to the change of the wind speed at different wind speeds, in order to not increase the additional load of the fan during shutdown, a wind wheel braking speed is set to represent that when the wind wheel speed is reduced to a certain value, the wind wheel is braked, so that the wind wheel enters an idle state at a lower speed, and then slowly stops to enter a standby state.

[0118] Specifically, referring to Figure 4 , the wind wheel braking speed is calculated according to the current fan operating state interval, including the following steps:

[0119] S431, according to the current fan operating state interval, confirming the current wind wheel speed and the size of the pitch angle.

[0120] S432, according to the preset pitch speed, calculating the time required to adjust the current pitch angle to the fully feathered state, and recording it as the feathering time.

[0121] S433, under the current wind speed, the gradient of the non-linear relationship between the wind wheel speed and the pitch angle is derived, and the gradient descent maximum direction is selected to calculate the speed increment coefficient.

[0122] S434, according to the speed increment coefficient and the feathering time, calculating and obtaining the wind wheel braking speed.

[0123] The preset pitch speed represents the speed of adjusting and rotating the pitch angle during shutdown. Different pitch speeds are given for different shutdown signals and abnormal risk levels. For example, the normal shutdown is adjusted at a speed of 4 degrees per second, the fast shutdown is adjusted at a speed of 5.5 degrees per second, and the emergency shutdown is adjusted at a speed of 7 degrees per second. The specific speed should be determined according to the actual situation, and the present application is not limited; the fully feathered state is the pitch angle of the fan in the standby state mentioned above, that is, about 90 degrees.

[0124] During normal shutdown process, the pitch angle is usually adjusted first to reduce the attack angle of the airflow to the blades, so as to reduce the rotation speed of the wind wheel. When the wind wheel is in grid-connected state, the wind wheel is disconnected from the grid when the rotation speed of the wind wheel is reduced to the preset grid-connected rotation speed. Finally, the wind wheel is idled until it stops and enters standby state or maintenance state after the rotation speed of the wind wheel is reduced to the preset safe rotation speed.

[0125] However, when the current wind speed is too fast or the rotation speed of the wind wheel is too fast, the rotation speed of the wind wheel has not reached the preset grid-connected rotation speed when the pitch angle is adjusted to the fully closed state, that is, near 90 degrees. In this case, the wind wheel should be braked. In addition to considering the current rotation speed of the wind wheel, when the current working state of the wind turbine is in the rated power continuous control interval, the pitch angle in this interval is continuously adjusted according to the change of the wind speed. Therefore, when the rotation speed of the wind wheel is reduced to a certain degree during shutdown, the corresponding braking is not a fixed state, and the current working interval of the wind turbine needs to be considered for adjustment and control.

[0126] Therefore, in the embodiment of the present application, the current rotation speed of the wind wheel and the size of the pitch angle are first determined according to the current working state interval of the wind turbine. When the wind turbine is in the rated power continuous control interval, the pitch angle is naturally adjusted according to the current pitch angle. When the wind turbine is in other working state intervals, the pitch angle is the minimum pitch angle, that is, 0 degrees. Then, the time required to adjust the pitch angle from the current pitch angle to the fully closed state is calculated according to the preset pitch speed, which is recorded as the pitch closing time. During shutdown, it is usually expected that the rotation speed of the wind wheel is continuously reduced during the pitch closing process, and the rotation speed of the wind wheel is reduced to below the grid-connected rotation speed or the preset safe rotation speed after the pitch closing is completed.

[0127] However, considering that the current rotation speed of the wind wheel is high, the rotation speed of the wind wheel may not reach a safe state after the pitch angle adjustment is completed. Therefore, braking needs to be performed at this time, that is, the state of the rotation speed of the wind wheel after the pitch angle adjustment is completed needs to be calculated.

[0128] Because, at the current wind speed, the wind wheel rotating speed is continuously decreased with the adjustment of the pitch angle, but the decreasing range is not linearly changed, but is a non-linear change process, so as to better control the braking time, an extreme case is taken as an estimate, that is, the gradient of the non-linear relationship between the wind wheel rotating speed and the pitch angle is derived at the current wind speed, the gradient descending maximum direction is selected to calculate the rotating speed increasing range coefficient, that is, the wind wheel rotating speed can be calculated to the fastest decreasing range, that is, the wind wheel braking rotating speed can be calculated according to the rotating speed increasing range coefficient, the wind wheel braking rotating speed at this time is the minimum rotating speed that the wind wheel rotating speed can reach after the pitch is closed, and then the braking is performed according to the wind wheel braking rotating speed, so as to at least ensure that the blade has completed the pitch closing when the braking is performed, and no additional load is generated after the braking.

[0129] It is worth noting that if the current wind turbine has not yet entered the grid-connected state, the shutdown of the wind turbine generally does not need to be braked at this time, mainly because the pitch is not fully opened and the wind wheel rotating speed is relatively low, at this time, only simple feathering adjustment is needed to slowly reduce the wind wheel rotating speed.

[0130] S500, based on the wind wheel braking rotating speed, performing shutdown control.

[0131] In the embodiment of the application, after the wind wheel braking rotating speed is obtained according to the current wind turbine working state, the wind wheel is braked according to the wind wheel braking rotating speed, so that the wind turbine can be stopped with the load being as low as possible.

[0132] Specifically, based on the wind wheel braking rotating speed, performing shutdown control, including the following steps:

[0133] S510, after receiving the wind wheel shutdown signal, adjusting the pitch angle to make the blade feather, and when the wind wheel rotating speed decreases to the wind wheel braking rotating speed, starting the wind wheel braking.

[0134] S520, after starting the wind wheel braking, when the wind wheel rotating speed decreases to the preset safe rotating speed, outputting the second prompt information.

[0135] The second prompt information indicates that the wind turbine has completed the shutdown operation.

[0136] In the embodiment of the application, after receiving the wind wheel shutdown signal, the pitch angle is adjusted to make the blade feather, at this time, the generator stops working on the wind wheel, the pitch closing operation is performed by adjusting the pitch angle, which makes the wind wheel rotating speed decrease, when the wind wheel rotating speed decreases to the wind wheel braking rotating speed, the wind wheel braking is started, and the wind wheel rotating speed continues to decrease until the wind turbine enters the idling state after decreasing to the set safe rotating speed, at this time, it can be considered that the shutdown has been completed, and therefore the second prompt information is outputted to give a corresponding prompt.

[0137] The embodiment of the application further provides a fan start-stop system, referring to Figure 5 The system comprises a wind wheel start speed acquisition module 101, a fan start module 102, a working state switching module 103, a wind wheel braking speed acquisition module 104 and a fan stop module 105.

[0138] The wind wheel start speed acquisition module 101 is configured to acquire the current wind speed after receiving a start signal, and estimate the wind wheel start speed according to the current wind speed.

[0139] The fan start module 102 is configured to adjust the pitch angle based on the wind wheel start speed, and wait for the wind wheel speed to reach a preset grid-connected speed to enter a grid-connected state.

[0140] The working state switching module 103 is configured to switch the running state of the fan by preset interval division after entering the grid-connected state.

[0141] The wind wheel braking speed acquisition module 104 is configured to acquire the current wind speed and confirm the running state interval of the current fan after receiving a stop signal, and calculate the wind wheel braking speed according to the running state interval of the current fan.

[0142] The fan stop module 105 is configured to perform stop control based on the wind wheel braking speed.

[0143] In the embodiment of the application, the wind wheel start speed acquisition module 101 is specifically configured to acquire the current wind speed after receiving a start signal, and estimate the wind wheel start speed according to the current wind speed.

[0144] The fan start module 102 is specifically configured to adjust the pitch angle based on the wind wheel start speed, and enter the grid-connected state with the best pitch angle after waiting for the wind wheel speed to reach a preset grid-connected speed.

[0145] The working state switching module 103 is specifically configured to switch the running state of the fan by preset interval division after entering the grid-connected state, so as to realize maximum wind energy capture benefit for different wind speeds.

[0146] The wind wheel braking speed acquisition module 104 is specifically configured to acquire the current wind speed and confirm the running state interval of the current fan after receiving a stop signal, and calculate the wind wheel braking speed according to the running state interval of the current fan.

[0147] The fan stop module 105 is specifically configured to reduce the wind wheel speed by adjusting the pitch angle, and also brake the excessively high wind wheel speed to reduce the additional loss of the fan caused by the imbalance of the wind wheel speed.

[0148] The embodiment of the application further provides a computer readable storage medium, which stores a computer program capable of being loaded by a processor and executing any one of the fan start-stop methods.

[0149] The embodiments of the specific implementation are the preferred embodiments of the application, and do not limit the protection scope of the application, so that: any equivalent changes made according to the principles of the application should be covered within the protection scope of the application.

Claims

1. A method of fan start-stop control, the method comprising: The method comprises the following steps: After receiving the start signal, the current wind speed is obtained, and the wind wheel start speed is estimated according to the current wind speed; Based on the wind wheel start speed, the pitch angle is adjusted, and the wind wheel enters the grid-connected state after the wind wheel speed reaches the preset grid-connected speed; After entering the grid-connected state, the running state of the wind turbine is switched through preset interval division; After receiving the shutdown signal, the current wind speed is obtained, and the running state interval of the current wind turbine is confirmed, and the wind wheel braking speed is calculated according to the current wind turbine running state interval; Based on the wind wheel braking speed, the shutdown control is performed, The wind wheel start speed is estimated according to the current wind speed, which comprises the following steps: The wind wheel start speed is set as a variable parameter; Through the preset initial pitch angle, the time from the wind wheel start speed to the preset grid-connected speed under the current wind speed is estimated, and the time is recorded as the first time; Through the preset grid-connected pitch angle, the time from the wind wheel start speed to the preset grid-connected speed under the current wind speed is estimated, and the time is recorded as the second time; Based on the first time and the second time, the time difference value is obtained, and is recorded as the speed deviation time; According to the speed deviation time, the preset pitch adjustment time is used to minimize the time difference value to construct a target function, and the wind wheel start speed is calculated through a preset method.

2. The fan start-stop control method of claim 1, wherein, Based on the wind wheel start speed, the pitch angle is adjusted, and the wind wheel enters the grid-connected state after the wind wheel speed reaches the preset grid-connected speed, which comprises the following steps: After the wind turbine starts, the pitch angle is adjusted to the preset initial pitch angle; When the wind wheel speed reaches the wind wheel start speed, the pitch angle is adjusted to the preset grid-connected pitch angle, and then the wind wheel speed is waited to rise; When the wind wheel speed reaches the preset grid-connected speed, the wind turbine enters the grid-connected state.

3. The method of claim 1, wherein, The running interval of the wind turbine comprises the initial grid-connected transition interval, the optimal tip speed ratio interval, the rated speed interval and the rated power continuous control interval, which are respectively recorded as the first interval, the second interval, the third interval and the fourth interval.

4. The fan start-stop control method of claim 3, wherein, The running state of the wind turbine is switched through the preset interval division, which comprises the following steps: When the generator power reaches the minimum power corresponding to the optimal tip speed ratio in the first interval, the second interval is cut in; When the generator power is lower than the minimum power corresponding to the optimal tip speed ratio in the second interval, the first interval is cut back, and when the wind wheel speed reaches the preset rated speed and the generator power continues to rise, the third interval is cut in; When the wind wheel speed drops below the preset rated speed in the third interval, the second interval is cut back, and when the generator power reaches the rated power and the wind speed continues to rise, the fourth interval is cut in; When the generator power drops below the preset rated power in the fourth interval, the third interval is cut back.

5. The method of claim 1, wherein, The shutdown signal is divided into normal shutdown signal and abnormal shutdown signal, and the current wind speed is obtained after receiving the shutdown signal, and the running state interval of the current wind turbine is confirmed, and the wind wheel braking speed is calculated according to the current wind turbine running state interval, which comprises the following steps: If the current shutdown signal is an abnormal shutdown signal, the source of the current abnormal shutdown signal is obtained, and the abnormal risk level is evaluated according to the current wind speed and the running state interval of the wind turbine; If the abnormal risk level reaches the preset risk level, a first prompt information is output, and the first prompt information indicates that the risk level is too high, and rapid shutdown or emergency shutdown needs to be performed. If the current shutdown signal is a normal shutdown signal, the current wind speed is acquired, and the running state interval of the current wind turbine is confirmed, and the wind wheel braking speed is calculated according to the current wind turbine running state interval.

6. A fan start-stop control method according to claim 5, wherein The wind wheel braking speed is calculated according to the current wind turbine running state interval, including: According to the current wind turbine running state interval, the current wind wheel speed and the size of the pitch angle are confirmed; According to the preset pitch speed, the time required for adjusting the current pitch angle to the fully feathered state is calculated and recorded as the feathering time; The non-linear relationship between the wind wheel speed and the pitch angle is gradient-derived under the current wind speed, and the maximum gradient direction is selected to calculate the speed increment coefficient; According to the speed increment coefficient and the feathering time, the wind wheel braking speed is calculated and acquired.

7. The method of claim 1, wherein, The shutdown control is performed based on the wind wheel braking speed, including: After receiving the wind wheel shutdown signal, the pitch angle is adjusted to make the blade feathered, and when the wind wheel speed is reduced to the wind wheel braking speed, the wind wheel braking is started; After starting the wind wheel braking, when the wind wheel speed is reduced to the preset safety speed, a second prompt information is output, and the second prompt information indicates that the wind turbine has completed the shutdown operation.

8. A fan start-stop control system, characterized by, Including: A wind wheel starting speed acquisition module (101) is configured to acquire the current wind speed after receiving a starting signal, and estimate the wind wheel starting speed according to the current wind speed; A wind turbine starting module (102) is configured to adjust the pitch angle based on the wind wheel starting speed, and wait for the wind wheel speed to reach a preset grid-connected speed to enter a grid-connected state; A working state switching module (103) is configured to switch the running state of the wind turbine through preset interval division after entering the grid-connected state; A wind wheel braking speed acquisition module (104) is configured to acquire the current wind speed after receiving a shutdown signal, and confirm the running state interval of the current wind turbine, and calculate the wind wheel braking speed according to the current wind turbine running state interval; A wind turbine shutdown module (105) is configured to perform shutdown control based on the wind wheel braking speed.

9. A computer readable storage medium, storing a computer program capable of being loaded and executed by a processor to perform a wind turbine start-stop control method according to any one of claims 1 to 7.

Images